Gas capacity and mileage questions

[TerminatorX5]

Originally Posted by TiAgX5

I've seen almost 26 gals on numerous fills (and I add 10 to 11 oz of Lucas Upper Cyl Lube before EVERY fill), at different stations everywhere from Florida to New Mexico, last one was on 8-20 in Coppell, TX..........

do you pre-pay? it seems that if you give the attendant $90, he makes sure you get the $90 worth of gas... just kidding...

in all honesty, i have no idea why it is so... possibly you top it off until the gas spills over, or you have "extended" version gas tank (don't think so), the atmospheric pressure is too high/low, and the volume measured is different, or, for real, the pump is not correctly calibrated...

[Qsilver7]

Originally Posted by e30cabrio

Thanks, yes I unlocked it to see voltage when my alternator went on hiatus. I would need to do 4 presses in test 20 if I find 18 is correct but I am showing 14?

No, I think you're misunderstanding TEST 20. If no one has changed your correction factor...it should read 1000 when you open TEST 20. Since the value can be anywhere from 750-1250...if you're at 1000...4 presses of the button would only reduce the number to 996. You have to enter correct values for the equation that is given so that you can find what "VK" is for your fuel consumption. It's really simple once you have your avg "actual" MPG...you divide that with the OBC's "displayed" MPG, then multiply that number by 1000. It should be a number somewhere between 750-1250. The number you come up with is what you should change TEST 20 to.

(see...your high school math teacher was right...someday you'd need to understand/use equations to figure out a problem)

VK= (actual mileage/display mileage) x 1000

As I mentioned in the previous post...the best way to do the correction value is to "average" out several fuel fill-ups of your normal driving habits/environment...then use that "actual MPG" as the variable in the corrective equation.

For example, as some others members have mentioned above...I keep track of every fuel fill-up...and you can see in the Excel file below...sometimes the actual MPG calculation matches the OBC's displayed MPG...sometimes it's off by a little over 1 MPG.

If the two calculations were way off by more than 2 MPGs...then I'd use my actual AVG MPG...not the highest MPG that I recorded to use in the correction equation {VK= actual MPG/displayed MPG) x 1000}.

[TiAgX5]

Originally Posted by TerminatorX5

do you pre-pay? it seems that if you give the attendant $90, he makes sure you get the $90 worth of gas... just kidding...

in all honesty, i have no idea why it is so... possibly you top it off until the gas spills over, or you have "extended" version gas tank (don't think so), the atmospheric pressure is too high/low, and the volume measured is different, or, for real, the pump is not correctly calibrated...

No attendants here in the southern US where I drive (might be why I don't have a single nozzle nick/dent in over 170k miles.

When you swipe your card at the pumps in Florida and Texas the max amount approved is $90, pump stops there.

I top off to the next 50 cents (I don't spill).

Having seen about 26 gal go in at different stations from FL to NM (plus the 10 or 11 oz of snake snot), at different times of the year (cool/hot, rain/dry) I doubt it's pump error. I can easily run 20 miles in the city after the OBC shows (---) miles to empty.

[e30cabrio]

Thanks For the table. I am reading on a phone, losing some input. Lol.

I have kept track of the 20 or so tanks I have put in so far. My drive to work is 12 miles street 14 freeway and I am averaging 13.8 mpg on those tanks. This was my first pure freeway trip. Over the 2 tanks average was 18.4.

I will continue to keep track and when I have more data ill run the numbers to plug into test 20. Thanks!

[bpowa]

Originally Posted by e30cabrio

Thanks For the table. I am reading on a phone, losing some input. Lol.

I have kept track of the 20 or so tanks I have put in so far. My drive to work is 12 miles street 14 freeway and I am averaging 13.8 mpg on those tanks. This was my first pure freeway trip. Over the 2 tanks average was 18.4.

I will continue to keep track and when I have more data ill run the numbers to plug into test 20. Thanks!

I have not gone through a full tank yet.. But the average mpg displayed is 19.2.. Mostly freeway. 70-75 mph. I would say it would probably average 16mpg.

What I normally do is fill the tank; reset the trip; and refill the tank again. Divide miles with gallons purchased. THis will give you almost the exact MPG.


I was getting 14.4 in my tundra. So If I get 16-17 on the x5 Im ok with it.

In a year one would save a few hundred dollars from driving a sedan.
IMO I keep track of mpg to see how efficient the vehicle is running.

[bcredliner]

IMO--Sharing our mileage here is less than meaningless. The way we do the calculations varies so much and we still leave a 50 gallon drum of other reasons that our comparisons don't compare and remain inaccurate.

I say compute mileage however you like, just do it the same way every time so the amount of inaccuracy is somewhat consistent.

For example, the OBC may not be accurate but any inaccuracy still works to see a trend over time--set it and forget it for 6 months. if it is higher than usual ignore it--it is a miracle. If it is lower, fill up the tank and reset the OBC the first time you are going to burn a few gallons on the freeway then check it to see how it compares to the last time you did the same thing. If it checks lower it might be time to start doing some checking to see if something that impacts mileage needs attention.

I would say that a good share of us tend to check mileage on a long trip to see what we can get with steady reasonable driving for a bunch of miles--that's the best I ever get because I use cruise control most of the time. I like looking forward to that magical moment than think about the miles I am putting on my vehicle.

I check my mileage by OBC so I can always make believe it is really much better because OBC is so inaccurate. I don't want the most accurate method there is as I might be more inclined to take it to heart. I don't want a lack of good mileage in today's world of better options to make a difference in what or how I drive, at least not until my X is no longer so gratifying and fun.

The following link, like others when you google best way to check gas mileage, explains a long standing commonly used method:
How to Calculate Gas Mileage - Green Transportation - MOTHER EARTH NEWS

Be sure to read the associated posts if you like a more scientific approach because we still have missed a bunch of other considerations we need to pull out of that 50 gallon drum to be less inaccurate.

[e30cabrio]

I was not asking for anyone to post their mileage. I was asking if my mileage seemed ok and what actual tank capacity is. I wanted to see if the wildly lesser displayed mileage was odd. As an aside, the second mpg screen is at 13.xx I have not reset it.

[jsoto]

I'm going to have to re-read this thread from the whole...

My last 2 fillups have been off. I'm thinking 6 gallons based on the needle, and I pump in 10. Other time, I was topping it off, I think around the same - 5 gallons, and I pumped in almost 9 or 10...

[Qsilver7]

Originally Posted by bcredliner

IMO--"Sharing" our mileage here is less than meaningless.

In the same vein...I would say that "comparing" our mileage here is less than meaningless.

I agree with you in that there are so many variables that are unaccounted when "comparing" our gas mileage. One of the biggest variables that is overlooked is MPH...which may indicate what type of traffic/driving conditions each of us may be encountering.

My driving experience is 95% all city/urban, stop-n-go traffic. There are very few instances that I'm on a boulevard or parkway with timed lights or long stretches of constant speed...or any highway/freeway driving. Thus...as can be seen in my chart above...my AVG MPH is 24.6...whereas others that live in a larger metropolitan area or rural area may have a higher AVG MPH which could make their AVG MPGs higher.

Then there's also geographical elevation above/below sea level, and other environmental/climatic variables that makes comparing our AVG MPGs "meaningless". Some of us may have a heavy foot and drive aggressively, whereas some of us may have "granny-toe"...so much so that ATC (adaptive tranny control) may hardly ever move from extreme economy mode.

But "sharing" how we track (the fact that some of us do track) our MPG/MPH may help others that may not have a good understanding of their OBC and the possible difference between the OBC and their actual tracking. Take the info for what its worth and measure it only to your circumstances...not by someone who may live & drive in a totally different environment.

[motordavid]

Not to drag this out, but...
From the Manual:

gas tank capacity is aprox 24.6 gals
Reserve is aprox 2 gals

Thus, one could stuff 26+ gallons in there, and tanks do vary somewhat over the course of the production run from the supplier.

So, more than 24.6 is obviously correct, for some.

jsoto: looking at your gauge and predicting how many gallons it will take is a leap of faith, and often inaccurate, in my experience, on any car.

GL, mD